Method and means for controlling drilling muds



ATES

I PATENT OFFICE METHWD SGF Lorena K. Ayers, St. Louis, Mo,

assignments, to National l York, N. Y a corporation of New No aw. he No. cassa- V a sci-component through the well in order to lubricate the drill bit and to carry the cuttings out of the hole. The drilling mud also often serves other functions as for instance a means for lining the wall of the bore hole to prevent the loss of water into the formation and to prevent caving of the wall and as a means for keeping down aas pressures.

In some instances the drilling mud is made up of water and cuttings or clay from the bore hole. In other instances special clays or other materials may be used to make up the body of the drilling mud so as to secure the desired characteristics of viscosity, specific gravity. etc.. necessary to carry the cuttinss out of the hole, to line the walls of the hole and to keep down gas pressures to prevent blowing out of the hole. In many instances the drilling mud has a high colloidal clay content due either to the nature of the formation in which the well is being drilled or to the addition of clay having a high colloidal content which will impart a high viscosity to the mud.

The. effect of dissolved metal salts, vprincipally calcium and magnesium, which carry a high electrical ionization charge is to sometimes exert a very great influence on the viscosity and gelling of the drilling muds so that although a mud may be made up of the proper amount of clay and other ingredients to produce the desired viscosity of drilling mud, when these calcium or magsett of the cuttings in the settling ditch. The

settling of the cuttings is not alone a matter of vty of the drilling mud but is also affected by the gelling characteristics of the mud.

it h therefore the object of my invention to provide a method and means for controlling the.

viscosiw and gelling of the mud within proper to ior satisfactory drilling of the well and to so balance the mud at all times as toprevent excve ionization of the salts dissolved therein and thereby prevent undesirable increases in visty or gelling characteristics of the mud. .Among the materials which havebecn found r, by means Com New Jersey cation June 6, 19%,

metal meta and pyrophosph'ates, such as sodium hexametaphosphate, poum metaphosphate, lithium metaphosphate, -onium metaphosphates and sodium py phosphates, the sulphuric acid esters oi the higher aliphatic alcohols.

While various materials having the property of repressing, sequestering or locking the calcium or m nesium or other ions into a soluble but substantially non-ionized condition are known, such as the alkali metal meta and pyrophosphates abovementioned, the sulphuric acid esters of the higher aliphatic alcohols, etc., I prefer to use sodium hexametaphosphate NaflNacPaOn) on account of its higher eficiency and lower cost for the purpose prescribed. and the sodium metaphosphate which 'is slightly acid contains an addition of a small amount of sodium pyrophosphate sumcient to neutralize the acidity of the sodium metaphosphate.

.03 of one (1) per cent. of sodium metaphosphate to a drilling mud having high gellation characteristics will quickly reduce the eel formation and at the same time lower the viscodty so as to permit ready settling of the drill cuttings in the settling ditch without, however, causing precipitation of any of the materials forming the body of the drilling mud itself.

While the material may be added in various ways, as by adding the solid salts directly to the drilling mud to become dissolved therein, or to the materials forming the mud, I prefer first to iorm them into a solution of the desired strength which solution is added gradually to the drilling mud,

The dilute solution is preferably added by drippina or running a small stream into the drillin: mud in the ditch or fiowline as it flows out a of the well where turbulence of the flowing mud is suiilcient to mix the dilute reagent throughout the mud with the furtheradvantage of allowing time for the reaction to become complete in the mud storage pits and thus to provide uniform amounts of the alkali metaphocpliate throughout the entire column of drllliul ml! b01118 circulated through the well.

It is also desirable under certain conditions toadd thematerialto themud in afinelypow-.

to prevent lumping. This can be accomplished by prinklingit intothemud'in thcditchel aait flows from the well thus allowing time for com- Dlete solution and uniform distribution before themud is'againpumped intothe well.

' suitable m the above purpose are the alkali ii one addition our matcriaiii usually an.

I have found that the addition of as little as cient to overcome the gelling characteristics of a mud. ere, however. calcium is being added to the mud in substantial amounts from the formation being drilled, it is necessary to make continued small additionssuflcient to keep the ionization oi the calcium in the mud below that at which coagulation or flocculation and high gellation oi the mud occurs. As the material acts in a manner proportionate to the quantities used on the calcium and magnesium or other salts in the drilling mud, any desired degree of suppression or non-suppression may be obtained by varying the amount of the metaphosphate added to the drilling mud, thus giving a very positive control over the gelling characteristics of the mud.

I claim:

1. A drilling mud for wells conteininii a gelcomponent and else isletsu and pyrophosphates with the proportion of the pyrophosphnte small compared to that oi the metaphosphate but sumcient to neutralize the acidity of the metaphos phate, the said salts being selected from the group consisting of allrali metal and ammonium mete end pyr phoshhates.

2. A drilling mud for wells containing a gelessence component end nlso sodium hesametaphosphate and sodium pyrophosphate with the proportion of sodium pyrophosphate small compared to that of the sodium heitametaphosphate but sumcient to neutralise the acidity of the sodium hexametaphosphate. V

3. In the art of drilling wells by the employmerit of e drilling mud containing a gel-component, the process comprising adding to such a dril mud meta and pyrophosphates with the proportion of the pyrophosphate small compared to that of the metaphosphate but sufllcient to neutralize the acidity of the metaphosphate, the sold salts being selected from the group consisting of metal and ammonium meta and pyrophosnhetes,

4:. In the out oi" drilling wells by the employment oi a drilling mud containing a gel-commoment, the process comprising adding to such a 20 drilling mud sodium heiiametaphosphate and 

